In recent years, techniques have been developed for protecting a passenger of a vehicle from a collision force acting on the vehicle. For enhanced passenger protecting performance, there has been a demand for reconsideration of the overall vehicle body structure including doors. As an example of a vehicle door designed to enhance the passenger protecting performance, there is known a “vehicle door structure” disclosed in Japanese Patent Laid-open Publication No. HEI-7-25236.
The disclosed vehicle door structure includes an opening portion in an upper area of a door body composed of inner and outer panels, and a window panel is provided in the opening portion for up-and-down movement through the opening.
To secure necessary structural rigidity of the opening portion, reinforcements are provided respectively in an upper portion of the inner panel and upper inner portion of the outer panel and extend along the opening portion. Each of these reinforcements has a recessed portion formed therein to be located forwardly of a hip point of the passenger. When an external force has acted on the door body from sideways of the vehicle, namely, a certain object has collided with a side door of the vehicle, the reinforcements deform plastically, at the position of the recessed portions, toward the interior of a vehicle compartment, so that the collision energy can be absorbed by the plastic deformation of the reinforcements. Thus, a collision impact applied to the passenger can be alleviated, which thereby enhances the passenger protecting performance of the vehicle door.
For the aforementioned vehicle door having the reinforcements designed to deform plastically towards the interior of the vehicle compartment when the external force acts on the vehicle door from sideways, however, the reinforcements are not designed allowing for occurrence of impact or collision on a front part of the vehicle. In other words, no measure is taken against application of an external force to the vehicle from a front side of the vehicle. There has been needed a vehicle door designed to ensure the enhanced passenger protecting performance even when the vehicle is subjected to the external force from the front side thereof.